Texas Instruments SN74CBT3245ADWG4

Overview

SN74CBT3245ADWG4 from Texas Instruments is an octal FET bus switch IC designed for high-speed TTL-compatible bidirectional data routing between two 8-bit ports (A and B). It features 5-Ω on-state resistance, 0.25 ns typical propagation delay at 5 V, and operates from 4 V to 5.5 V supply. It is used in address/data bus isolation, hot-swap I/O buffering, and level-translating logic interfaces.

For engineers reviewing the SN74CBT3245ADWG4 datasheet, SN74CBT3245ADWG4 pinout, SN74CBT3245ADWG4 application, or SN74CBT3245ADWG4 equivalent, key selection criteria include its low on-resistance, sub-nanosecond enable/disable timing, standard '245 pin compatibility, and operation across −40°C to 85°C industrial temperature range.

Technical Context

The SN74CBT3245ADWG4 implements eight independent analog switches using NMOS FETs with no internal level-shifting circuitry-functioning as a passive, bidirectional, voltage-following bus switch. Its control logic is TTL-compatible: OE low enables A↔B conduction; OE high places both ports in high-impedance isolation.

It lacks internal ESD protection diodes beyond standard process limits and requires external pull-up on OE for power-up/down high-Z assurance. The device does not buffer or regenerate signals-it passes voltage levels directly, making it suitable only where source and load share compatible voltage domains.

Key Specifications

Pinout & Package

SN74CBT3245ADWG4 is packaged in a 20-pin SOIC (DW) package, 7.5 mm × 12.8 mm body, 1.27 mm lead pitch, 2.65 mm max height, RoHS-compliant, with NiPdAu lead finish and JEDEC MS-013 registration.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bus switch applications.

Compared with SN74CBT3245ADWG4, SN74CBTD3384ADW adds dual-supply level translation at the cost of higher complexity and non-drop-in layout, while 74LVC245APW provides buffered direction-controlled drive but cannot replace passive, low-latency, bidirectional switching in timing-critical isolation roles.

Availability

SN74CBT3245ADWG4 is available at Aetrix Electronics and suitable for industrial control backplanes, embedded test instrumentation, and programmable logic I/O expansion requiring stable component supply, long-lifecycle support, and verified SOIC packaging.

Supply support for SN74CBT3245ADWG4 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a U.S.-based semiconductor company specializing in analog, embedded processing, and logic solutions with broad industrial and automotive qualification.

The SN74CBT3245ADWG4 belongs to the CBT (Crosspoint Bus Transceiver) family, engineered for ultra-low-latency, passive bus switching in high-speed digital systems where signal integrity and timing predictability are critical.

FAQ

What is the maximum continuous current per channel for SN74CBT3245ADWG4?

The SN74CBT3245ADWG4 supports up to 128 mA continuous channel current per switch path, as specified in its absolute maximum ratings. This rating applies under steady-state DC conditions with proper thermal management. Exceeding this current may cause irreversible junction heating or parametric shift. Derating is recommended above 70°C ambient, and the 5-Ω on-resistance implies ~0.64 V drop at 128 mA - verify voltage margin at the load.

Does SN74CBT3245ADWG4 support level translation between different supply voltages?

The SN74CBT3245ADWG4 does not perform active level translation - it is a passive FET switch that passes voltage levels directly. It can interface ports operating at the same V_CC (4–5.5 V), but connecting A and B to different supplies risks latch-up or damage unless external clamping is added. For true bidirectional level shifting, TI recommends SN74CBTD3384ADW instead.

Is SN74CBT3245ADWG4 pin-compatible with standard 74-series '245 devices?

Yes, SN74CBT3245ADWG4 uses the standard '245-type pinout (A1–A8, GND, V_CC, OE, B1–B8, NC) in its SOIC-DW package, matching 74LS245, 74HC245, and 74ACT245 footprints. However, its internal architecture differs: it lacks direction control and 3-state outputs, functioning instead as an OE-gated bidirectional analog switch - verify system logic compatibility before substitution.

What is the recommended OE pull-up resistor value for SN74CBT3245ADWG4?

Texas Instruments recommends tying OE to V_CC via a pull-up resistor to ensure high-impedance state at power-up. The minimum value depends on the driver's current-sinking capability; for standard TTL or CMOS drivers, 4.7 kΩ to 10 kΩ is typical. Lower values improve noise immunity but increase static current; values below 1 kΩ are unnecessary and waste power. Always confirm with the controlling GPIO's I_OL spec.

Can SN74CBT3245ADWG4 be used in hot-swap applications?

Yes - SN74CBT3245ADWG4 is widely deployed in hot-swap I/O modules due to its fast disable time (2.1 ns), high off-impedance (>1 GΩ), and robust overvoltage tolerance (−0.5 V to 7 V on I/O pins). To ensure safe insertion, OE must be held high until V_CC stabilizes, and series current-limiting resistors (e.g., 10–33 Ω) are advised on A/B lines to suppress transient inrush.